Validity Of Urine Specific Gravity When Compared With Plasma Osmolality As A Measure Of Hydration Status In Male And Female NCAA Collegiate Athletes

ASU Author/Contributor (non-ASU co-authors, if there are any, appear on document)
Steven McAnulty PhD, Professor (Creator)
Appalachian State University (ASU )
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Abstract: The purpose of this study was to evaluate the response of urine specific gravity (Usg) and urine osmolality (Uosm) when compared with plasma osmolality (Posm) from euhydration to 3% dehydration and then a 2-hour rehydration period in male and female collegiate athletes. Fifty-six National Collegiate Athletic Association (NCAA) wrestlers (mean ± SEM); height 1.75 ± 0.01 m, age 19.3 ± 0.2 years, and body mass (BM) 78.1 ± 1.8 kg and 26 NCAA women's soccer athletes; height 1.64 ± 0.01 m, age 19.8 ± 0.3 years, and BM 62.2 ± 1.2 kg were evaluated. Hydration status was obtained by measuring changes in Posm, Uosm, Usg, and BM. Male and female subjects dehydrated to achieve an average BM loss of 2.9 ± 0.09% and 1.9 ± 0.03%, respectively. Using the medical diagnostic decision model, the sensitivity of Usg was high in both the hydrated and dehydrated state for males (92%) and females (80%). However, the specificity of Usg was low in both the hydrated and dehydrated states for males (10 and 6%, respectively) and females (29 and 40%, respectively). No significant correlations were found between Usg and Posm during either the hydrated or dehydrated state for males or females. Based on these results, the use of Usg as a field measure of hydration status in male and female collegiate athletes should be used with caution. Considering that athletes deal with hydration status on a regular basis, the reported low specificity of Usg suggests that athletes could be incorrectly classified leading to the unnecessary loss of competition.

Additional Information

Sommerfield, Lesley M.; McAnulty, Steven R.; McBride, Jeffrey M.; Zwetsloot, Jennifer J.; Austin, Melanie D.; Mehlhorn, Jonathan D.; Calhoun, Mason C.; Young, Juliane O.; Haines, Traci L.; Utter, Alan C. (2016). Validity of Urine Specific Gravity When Compared With Plasma Osmolality as a Measure of Hydration Status in Male and Female NCAA Collegiate Athletes. The Journal of Strength & Conditioning Research, August 2016 - Vol. 30, Iss. 8, pages 2219-2225. doi: 10.1519/JSC.0000000000001313. Publisher version of record available at:
Language: English
Date: 2016
dehydration, urine osmolality, division I athletes, hydration

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